Piston cushioning structure



June 9, 1964 H. K. RADER PIsToN CUSHIONING STRUCTURE 2 Sheets-Sheet 1 Filed Jan. 29, 1962 INVENTOR.

June 9, 1954 H. K. RADER 3,136,225

PIsToN cusHIoNING STRUCTURE Filed Jan. 29. 1962 2 Sheets-Sheet 2 ffl/'g2 wilg W21: 54 62 w? 2lL 'diri A TOR 4Q flfa @off United States Patent O 3,136,225 PISTON CUSHIONING STRUCTURE Harold K. Rader, 1826 Martin Ave., Port Huron, Mlch. Fried Jan. 29, 1962, ser. No. 169,202 Claims. (Cl. 91-395) The present invention relates to piston and cylinder structure and refers more specifically to improved structure for cushioning a piston reciprocally mounted in a cylinder operable to provide maximum cushioning length and improved sealing means therefor.

In the past the cushioning of pistons reciprocal within cylinders has been deficient in that ecient means have not been readily available for adjusting the position of the piston within the cylinder at which cushioning is initiated. Further wherein such means have been provided they have been restricted to relatively short cushioning lengths at each end of the piston. In addition, with previously provided adjustable cushioning means excess leakage of cushioning medium from the cylinder has sometimes occurred.

It is therefore one of the objects of the present invention to provide improved means for cushioning a piston which is reciprocal within a cylinder including means for adjusting the position of the piston in the cylinder at which cushioning is initiated.

Another object is to provide cushioning structure for a piston reciprocal within a cylinder capable of providing cushioning of the piston over sub-stantially the entire stroke of the piston.

Another object is to provide piston cushioning means for a pistonr reciprocal within a cylinder comprising a cushioning plate supporting rod reciprocally mounted within the piston rod for axial movement with respect thereto, a cushioning plate secured to the end of the supporting rod, and resilient means positioned between the cushioning plate and piston cooperable with a spring pressed abutment protruding through the adjacent end of the cylinder to provide cushioning of the cylinder at a predetermined piston position determined by the bias applied tothe spring pressed abutment.

Another object is to provide piston cushioningl means as set forth above and further including an annular sealing ring secured to the surface of the adjacent end of the cylinder.

Another object is to provide piston cushioning means as set forth above wherein the abutment is located radially inwardly of the annular sealing ring.

Another object is to provide structure as set forth above wherein the abutment is located radialy outwardy of the annular sealing ring.

Another object is to provide means for cushioning a piston which is simple in construction, economical Ato manufacture and eilcient in use.-

Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawings, illustrating a preferred embodiment of the invention, wherein:

FIGURE 1 is a diagrammatic longitudinal section View of cylinder and piston structure including piston cushioning means constructed in accordance with the invention.

FIGURE 2 is a transverse section of the cylinder and piston structure illustrated in FIGURE 1 taken substantially on the line 2 2 in FIGURE l.

FIGURES 3 and 4 are partial longitudinal section views similar to a portion of FIGURE 1 illustrating modifications of the cylinder and piston structure of FIGURE 1 wherein the abutment is ececntric with respect to the cushioning plate and radially within and exterior of the annular seal, respectively.

v3,136,225 Patented June 9, 1964 With particular reference to the iigures, one embodiment of the present invention will now be described 1n detail.

As shown best in FIGURE 1, the cylinder and piston Structure 10 includes the cylinder 12 and the piston 14 reciprocally mounted within the cylinder 12 on the piston rod 16. The cushioning means 18 and 20, as shown, are provided to cushion the piston 14 in its reciprocal movement over substantially the entire stroke thereof from the center position in either direction. Sealing rings 22 and 24 are provided in the end walls 26 and 28 of the cylinder 12, as shown, to provide more eflicient sealing in conjunction with the cushioning means 18 and 20 respectively, as will be considered in more detail subsequently.

More particularly, the cylinder 12 includesthe tubular member 30 having annular recesses 32 and 34 at opposite ends thereof in which the O-rings 36 and 38 are secured. The O-rings 36 and 38 in conjunction with the collars 4t) and 42 and the bolts 44 positioned angularly thereabout serve to -secure the end walls 26 and 28 to the tubular member 38.

The end wall 26 includes the angularly spaced circumferential openings 46 extending therethrough through which the bolts 44 extend into the aligned threaded through openings 48 in the collar 4t). Additionally, the end wall 26 has an air exhaust passage 50 extending rst radially and then axially therethrough as shown in FIG- URE 1. The inner face 52 of the end wall 26 is provided with an annular recess 54 substantially centrally thereof in which the annular sealing-member 22 is secured. Sealing member 22 is particularly adapted to provide an eiiicient seal between the sealing disc or cushioning plate 56 of the cushioning means 18 and the end Wall 26 as will be considered subsequently.

End Wall 26 of the cylinder 12 in addition is provided with a variable diameter opening 58 extending therethrough in which the abutment 60 having the annular llange 62 therearound is secured. Abutment 60 is urged to the right in FIGURE 1 by means of the resilient spring 64, the bias of which may be adjusted by the adjustable screw 66.

The end wall 28 of the cylinder 12 includes a stepped opening 68 therethrough in which the packing 70 is secured'by the nut 72 to provide reciprocal mounting means for the piston rod 16 in the cylinder and piston construction 10. The enlarged diameter recess 74 in the end wall 28 together with the radially extending passage 76 communicating therewith provides an entry and escape passage for piston actuating medium. 1

Annular sealing ring 24 which is similar to sealing ring 22 is secured in the annular recess 78 in the end wall 28 of the cylinder 12, as shown best in FIGURE 1. y Sealing ring 24 acts in conjunction with the cushioningl plate 80 to provide more eiicient piston cushioning-by limiting the leakage of piston actuating medium after sealing has been accomplis-hed as will be considered subsequently.

The abutment 82 is urged to the left by the resilient spring means 84, the bias of which is adjustable, by the screw 86, all of which are secured in the variable diameter recess 88 in the cylinder end wall 28, as previously considered in conjunction with the abutment 60. Also, as previously considered in conjunction with the end wall 26, the end wall 28 includes the angularly spaced axially extending openings 90 therethrough adapted to align with the threaded openings 92 in the collar 42 whereby the end wall 28 may be secured to the collar 42 and thus the tubular member 30 by the bolts 44. a

It will be noted `that the abutments 60 and 82, as shown, may be positioned centrally of the end walls 26 and 28 or eccentrically with respectthereto. Further, the abut-` ments 6@ and 82 may be positioned either radially inwardly or outwardly of the sealing rings 22 and 24. Difcushioning action for a given spring bias, particularly if the cushioning plate is pivotally mounted as is plate S6 so thatV tilting of the cushioning plate is possible in operation.

Piston 14 includes the rigid disc 94 having the annular recess 9; inthe outer periphery thereof in which the sealing ring 98 is secured. Disc 94 also has the centrally located opening 160 extending axially therethrough, through which the reduced diameter threaded end 102 of the piston rod 16 extends. The disc 94 is secured on the reduced diameter end of the piston rod 16 between the annular spring retaining clips 104 and 106 by means of the nut 108, as shown.

The cushioning means`2il includes the annular cushioning plate Si) having the annular L-shaped member 111B secured thereto to retain the seal 112 for preventing leakage of thecushioning median into the recess 74 around the piston rod 16 in operation. The cushioning plate 8i? further includes a spun-over outer circumference 114 securely gripping an end convolution 116 of the spring 118. The other end of the spring 11S is similarly gripped by the spring retaining clip 104i,V as shown best in FIG- URE l.

Cushioning means 18 includes the cushioning plate 56 supported on the supportrod 12@ which, as shown, is reciprocally mounted in the axially extending recess 122 in the piston rod 16. The cushioning plate 56 is mounted for pivotal movement on the support rod 121i by means of the spherically contoured head 124 provided on the support rod 121) and the mating spherically contoured plate 126 secured to the cushioning plate. The spring 128 is provided between the piston disc 94 and the cushioning plate 56, as shown in FIGURE 1, and is secured to the outer lcircumference of the cushioning plate 56 and the outer circumference of the spring retaining clip 166 by spinning the outer circumferences thereof around the end convolutions of the spring.

In over-all operation when the piston is moved tot the right from the position illustrated, the cushioning plate St) iirst engages the abutment 82. VOn further movement ofV the piston rod and piston to the right in FIGURE 1, the cushioning plate Si) will be prevented from following such movement until the force applied to the abutment 82 through the spring 118 is equal to the force applied to the abutment 82 by the spring 84. After 'this balance has been reached, further movement of the piston to the right and subsequent movement of the cushioning plate Si! to the right will cause the cushioning plate Si) to seat on the sealing ring V24 to prevent further escape of the piston actuating median through the recess 74 and passage 76.

On movement of the piston 14 to the left in FIGURE 1, the abutment 60 is first engaged by the cushioning plate 56. Subsequent movement of the piston 14 to the left will cause compression of the spring 128 and consequent movement of the supporting rod 12@ intov the passage 122 in the piston rod 16 until the forces exerted on the abut-` ment 60 by the springs 128 and 64 are balanced. After a balance has been reached between the forces acting on the abutment k61), further movement of the piston 14 to the left will cause the cushioning plate 56 to seat on thesealing ring22 to prevent further discharge of piston actuating median through the passage 50; The remaining median in the cylinder 12 thus, provides cushioning for the piston.

It will be understood that the axial position of the piston 14 in the cylinder 12 at which the cushioning plates are permitted to seat on the sealing rings may be varied by adjusting the bias applied to the abutments by the adjusting screws 66 and 86 respectively. Further, it will be seen that in accordance with the invention the cushionwherein the length of cushioning was limited to approximately four inches due to structural limitations on the distance at which a cushioning plate could be positioned from the piston 14.

Further, the cylinder and piston of the invention are substantially more eicient than previous pistonand cylinder constructions in the provision of cushioning since the annular seals 22 and 24 provide positive sealing of the ends of the cylinders with, a minimum of pressure. In contrast, former metal-to-metal sealing surfaces between the cushioning plates and cylinder end walls permitted more or less leakage of piston actuating median due to roughness or warping of the mating faces.

The modifications of the cylinder and piston structure 1i) illustrated in FIGURES 3 and 4 provide eccentric mounting of the abutment 60 with the abutment 6i) being radially within and radially exterior of the annular seal 22, respectively. inasmuch as the modifications are exactly the same as the cylinder and piston structures shown in FIGURE 1 except for the location of the abutment 60 and the apparatus for variably biasing it inwardly of the cylinder and piston structure the same reference numerals have been used to indicate corresponding parts in all the iigures. The eccentric abutments obviously have the advantage of being able to hold the cushioning plate displaced from the seal 22 for a variable time for a given force provided against the abutment et) by the spring 64 depending on their radial distance from the center of the cushioning plate.

The drawings and the foregoing specification constitute a description of the improved piston cushioning structure in such full, clear, concise and exact terms as to enable any person skilled inthe art'to practice the invention, the scope of which is indicated by the appended claims.

What 1 claim as my invention is:

l. A cylinder including a pair of opposite end walls one of which includes an escape passage for piston actuating media, a piston rod reciprocally mounted in the other of said end walls one end of which extends into the cylinder and includes an axially extending recess therein, a piston secured to said one end of said piston rod for reciprocal movement within said cylinder, and cushioning means for said piston operable over substantially the entire stroke of the piston including a support rod one end of which is supported for telescopic movementwithin the recess in the one end of the piston rod, a cushioning plate secured to the other end of theV support rod exterior of the recess adapted to close said passage in said one end wall on movement ofthe piston toward said one end wall and resilientY means connected between the piston and the cushioning plate.

2. Structure as claimed in claim 1 and further including an annular seal in the one end wall of the cylinder surrounding the passage andengageable with the cushion plate.

3. Structure as claimed in claim 1 and further including means for varying the axial position of the piston at which the cushioning plate closes the passage.

ing plates, since they are supported on both sides of the piston 14, may be positionedat a substantial distance from the pistonilf-l. This is in contrast to prior constructions 4. Structure as claimedin'claim 3 wherein the means for varying the axial position of the piston at which the cushioning plate closes the passage comprises an abutment extending through said one cylinder end wallwhich is variable biased toward said cushioning plate whereby the cushioning plate is prevented from closing the passage until the bias applied to the abutment due to the resilient;

means between the piston andcushioning plate is greater than the bias urging the abutment toward the cushioning plate. Y,

5.` Structure as claimed in claim 4 and further including an annular seal in the one end wall of the cylinder surrounding the passage and engageable with the cushioning plate. .I l

6. Structure as claimed in claim 5 wherein the annular Y seal, abutment and cushioning plate are concentric.

7. Structure as claimed in claim 5 wherein the cushioning plate is pivotally mounted on the supporting rod and the abutment is mounted in the one end wall eccentric to the cushioning plate.

8. Structure as claimed in claim 5 wherein the abutment is eccentric with respect to the cushioning plate and radially within the annular seal.

9. Structure as claimed in claim 5 wherein the abutment is eccentric with respect to the cushioning plate and radially exterior of the annular seal.

10. A cylinder including a tubular body member and a pair or" end walls secured to the opposite ends of the tubular member, an escape passage for piston actuating media in each end wall of the cylinder, a spring biased abutment extending through each end wall of the cylinder into the interior thereof, an annular seal secured to the inner surface of each end wall surrounding the passage in the respective end wall, a piston rodv reciprocally mounted in one of said end walls one end of which extends Within the cylinder and includes an axially extending recess therein, a piston secured to the one end of the piston rod for reciprocal movement within the cylinder,

a cushioning plate mounted on the piston rod for rnovement axially thereof into engagement rst with the abutment and then with the seal associated with said one end wall to close the escape passage therein, a compression spring connected to the cushioning plate and the piston, a support rod one end of which is mounted for axial reciprocation within the recess in the piston rod, a second cushioning plate pivotally mounted on the other end of the support rod for movement therewith into engagement first with the abutment and then with the seal associated with the other end Wall to close the escape passage therein, and a second compression spring secured to the second .cushioning plate and to the piston, and means for varying the bias applied to the abutments positioned externally of the cylinder.

References Cited in the le of this patent UNITED STATES PATENTS 1,604,548 Dapron Oct. 26, 1926 2,556,698 Loewe June 12, 1951 2,986,120 Murek May 30, 1961 2,993,475 Ottestad July 25, 1961 3,034,482 Rader May 15, 1962 

1. A CYLINDER INCLUDING A PAIR OF OPPOSITE END WALLS ONE OF WHICH INCLUDES AN ESCAPE PASSAGE FOR PISTON ACTUATING MEDIA, A PISTON ROD RECIPROCALLY MOUNTED IN THE OTHER OF SAID END WALLS ONE END OF WHICH EXTENDS INTO THE CYLINDER AND INCLUDES AN AXIALLY EXTENDING RECESS THEREIN, A PISTON SECURED TO SAID ONE END OF SAID PISTON ROD FOR RECIPROCAL MOVEMENT WITHIN SAID CYLINDER, AND CUSHIONING MEANS FOR SAID PISTON OPERABLE OVER SUBSTANTIALLY THE ENTIRE STROKE OF THE PISTON INCLUDING A SUPPORT ROD ONE END OF WHICH IS SUPPORTED FOR TELESCOPIC MOVEMENT WITHIN THE RECESS IN THE ONE END OF THE PISTON ROD, A CUSHIONING PLATE SECURED TO THE OTHER END OF THE SUPPORT ROD EXTERIOR OF THE RECESS ADAPTED TO CLOSE SAID PASSAGE IN SAID ONE END 